Dell Latitudes are a solid purchase, Latitude being their premium business range, so they are much better built than the consumer stuff you would buy in PC world etc.
14" option, something like this is a very good laptop for the price:
http://www.ebay.co.uk/itm/1080p-Dell...Y-hga#viTabs_0
Decent i5 processor, sufficient ram, and a 256gb SSD
if you want something a bit bigger here is a 15" option, also comes with a better CPU and more ram, but without an SSD(its something you can add at a later date if you want):
send them an offer at 500£ and you will likely get a deal...
http://www.ebay.co.uk/itm/Dell-Latit...AAAOSwmCVY~hjq